NZUS93 KDLH 211801 LLLDLH MNZ010>012-018>021-025-026-033>038-WIZ001>004-006>009-220601- Public Information Statement National Weather Service Duluth MN 101 PM CDT Wed May 21 2025 Area Forecast Discussion National Weather Service La Crosse WI Issued by National Weather Service Duluth MN 100 PM CDT Wed May 21 2025 .KEY MESSAGES... - Showery/drizzly into this evening with many areas seeing another 0.10 to 0.25 before drier air moves in for Thursday. - Depending on cloud cover, light winds could promote some frost late tonight in north-central Wisconsin and in central north-central Wisconsin on Friday morning. - The Memorial Day weekend continues to look cooler than normal with high temperatures in the 60s and low temperatures in the lower and mid-40s. Still plenty of uncertainty on rain chances. && .DISCUSSION... Issued at 100 PM CDT Wed May 21 2025 This Afternoon and Tonight Into this evening, a trough of low pressure will extend across the Upper Mississippi River Valley from a departing low moving across the southern Great Lakes and another low pressure over southeast North Dakota and northwest South Dakota. This will keep showers and drizzle located over the area into this evening. Additional rainfall amounts this afternoon and evening will range from a tenth to a quarter of an inch. High temperatures will range from the mid-40s to lower 50s. The clouds will linger south of Interstate 94 tonight and there will be some partial clearing overnight north of this interstate as drier advects into the region. Winds speeds under a nocturnal inversion will generally range from 5 to 10 mph. The 10th to 90th percentiles has low temperatures north of Interstate 94 ranging from the mid-30s to around 40 and in the lower to mid-40s for the remainder of the area. With surface dew points drying overnight, there remains uncertainty on whether frost will be able to develop north of Interstate 94 tonight. If frost does happen to develop, it will be scattered to areas in north-central Wisconsin. Thursday and Thursday Night A closed low pressure area will retrograde southwest across the northern and western Great Lakes. There will likely be some sunshine during the early and mid-morning and then as diurnal heating occurs 900-800 mb lapse rates will become very steep (8-9 C/km). As this occurs, a 3-5K stratocumulus deck will quickly form for the late morning and afternoon. There may be a few isolated showers. High temperatures will range from the mid-50s to lower 60s. With the loss of diurnal heating on Thursday evening, skies will gradually clear. While we are losing the lower clouds, there will also be a scattered to mid-deck aloft. This adds to the uncertainty on how cold that we might get. North of Interstate 94, the 10th to 90th percentiles range from the lower 30s to around 40, and from around 40 to mid-40s elsewhere. If frost does happen to develop, it will be scattered to areas in central and north-central Wisconsin. Saturday Night into Tuesday There will be a ridge of high pressure centered over Hudson Bay and there will be a trough extending from the Great Lakes westward into the Dakotas. There will be a chance of showers and maybe a few storms near the base of this trough. Most (94%) of the GEFS members have this precipitation over much of our area. Meanwhile, just 24% of the ECMWF ECE has this precipitation. High temperatures will be in the 60s and low temperatures will be in the lower and mid-40s. At this time, it is looking like La Crosse WI will see their coolest Memorial weekend since 2013 (3-day average of 55.5F) and Rochester, MN will see their coolest Memorial Day weekend since 2021 (3-day average of 54F). && .AVIATION /18Z TAFS THROUGH 18Z THURSDAY/... Issued at 1220 PM CDT Wed May 21 2025 IFR to MVFR conditions will continue for the TAF sites into tonight as a trough lingers across the area. Numerous showers will be seen into this evening. While drier air will moving into the region overnight, low level moisture will likely remained trapped underneath a nocturnal inversion. This inversion should break around 22.14z. There will be likely be a brief period of scattered low clouds and then as diurnal heating occurs 900-800 mb lapse rates will steepen and a broken to overcast 3-5K deck of clouds will quickly develop. Winds will be north around 10 knots through this evening and then become northwest and increase to 10 to 15 knots on Thursday morning. $$ && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ DISCUSSION...Boyne AVIATION...Boyne